This invention relates to a process and an associated apparatus for treating sintered carbide metals to improve their structural characteristics at the molecular level. This process is used most advantageously to treat carbide cutting tools and other carbide parts that are, as part of their function, subject to abrasive and corrosive wear and degradation. Tools and parts treated according to the process of this invention demonstrate substantially improved durability and longer tool life than untreated tools and parts.
Sintered carbides are products of powder metallurgy, made of finely divided hard particles of carbide of refractory metal, sintered with one or more metals of the iron group (Fe, Ni, or Co) forming a body of high hardness and compressive strength. Ultimately, most carbide compositions contain basically four components: tungsten carbide, tantalum/niobium carbide, titanium carbide, and cobalt. Each of these is added to give the cutting tool a specific characteristic: strength, toughness, wear resistance at low temperature, chemical wear resistance at high temperature or resistance to deformation at high temperature. Unfortunately, each of these components brings several undesirable properties. And, in an attempt to ameliorate the undesirable properties, cryogenic processes have been developed to improve the durability and service life of all carbide products. To a certain extent, prior art processes have been successful in improving the performance of carbide metal cutting tools; but, as a result of continued experimentation, we have found it beneficial to take additional steps to make an even more durable and serviceable carbide product.